As you work your way through zone 6 you'll eventually come to the Badasses. You'll see Badassette first, but you will deal with her second, so for the time being ignore her. Continue working your way down the map and move towards the left hand side of the screen.

When you come across Badass, there will automatically be a cutscene where he'll talk about how he misses his partner, and how he wants to see her again.





You can grant him this wish rather easily by zooming the map out (right shoulder button on the Xbox 360 controller).


Once you've done so, he will happily kill himself :)

Having defeated Badass, you now have to defeat Badassette before you can progress through the game. However, in order to do this, you need to visit the shop that was previously locked.




You should have a ♥♥♥♥♥♥♥♥♥ available to you called Lovethong, make sure to pick this up...along with anything else you might want.

Once you've bought everything you need, exit the shop and press the back button on your controller to access the customisation menu. Equip the Lovethong skin.




You're now ready to face Badassette!

Once you have the Lovethong skin equipped you only have to come into view of Badassette and another automatic cutscene will take place, where Badassette opens the "window" for you.




Jump through the "window" and kill her...I used a simple and gory spin attack,





Within a few seconds you'll have defeated her, and the door requiring 52 bosses to be killed will have opened!